Multiple box fin



July 29, 1958 v 'B. SMITH 2,845,026" j MULTIPLEBOX FI'N Filed Nov. 1'2,v 195s 3 Shets-Shee; 1

# INVENTOR.

BERNARD SM| TH ATTORNEYS July 29, 1958 B. SMITH MULTIPLE BOX FIN- 3 Sheets-Sheet 2 Filed NOV. 17, 195 5 INVENTOR. BERNARD SMITH a 4, M4 ATTORNEYS July 29, 1958 sMm-I MULTIPLE BOX FIN 3 Sheets-Sheet 3' Filed Nov. 17, 1953 INVENTORI. b BERNARD SMITH BY G/fiw ATTORNEYS meiit o'fany royalties-thereon or therefor.

U e States P e 2,845,026 MUL'rIrL BoxFIN Bernard Smith, ChinaLake, Calm, assignor to the-United States ofAmrica as represented-by .the Secretary of the Navy 'T he' inve'ntion described herein may be manufactured and used'by or for theGovernrnent'o'f'the Uriit'e'dStates of America for governmental purposes without the pay- This invention-relates to'air-missile's and mor'e'p'articularly to improvements in stabilizing fins employed on relatively large and long range rockets, and specifically, to fins employed on the booster motor of a two stage rocket.

In a missile employing the present invention, severe I requirements were imposed upon its fin construction. It

was required, for example, that each fin be five feet in length at its base and extend outward therefrom two and one half feet, have a 45 leading edge sweepback, withstand a transverse load of one ton, a set back load of two tons, a skin temperature of 650 F. and maintain a straightness tolerance of less than these values being approximate. To meet these severe requirements, available fin designs would require as many as several thousand parts, such constructions, of course, being extremely complicated and expensive.

The principal object of this invention is to provide a simple and inexpensive fin which meets requirements of the order aforesaid.

, Another object is to provide a finconstruction, the parts of which may be readily assembled and welded together on a suitable jig adapted to maintain requisite tolerances,

thus rendering same subject to mass production by relatively unskilled mechanics.

Another object is' to provide a novel support construction between the base of the fin and a rocket nozzle.

Still further objects, advantages and salient features will become more apparent from the description to follow, the appended claim and the accompanying drawing, in which: i Fig. 1 is a fragmentary side elevation of the rear end of a rocket motor and a fin attached thereto, portions being broken away;

Fig. 2 is a rear elevation of Fig. 1 as viewed in the direction of arrow 2;

Fig. 3 is an exploded perspective'of the various components of the fin;

enlarged section taken on line 55,

on line 77,

enlarged section taken on line 8-8,

Fig. 3, the fin which forms the'subject of the invention comprises, in general, a front spar 10, a rear spar 11, a diagonal strut 12, a plurality of hollow sections 13, 14,

15, 16 within which the spars and struts are disposed,

.2 frontand rear webs '17, 18 for closing front and rea'r ends, respectively, of the hollow sections, a leading edge-Wedge 19, formers 20, '21, 22 for closing the inner endsof wedge 19 and section 13, a former 23 for closingfthe outerend erweuge 19, and a pair of plates 24, 25, to which the inner ends of spars 1'0, 11 are secured, respectively.

Section 13, as best'shown in Figs. 1, "4" and 6, is formed of sheet metal, bent into the form of a'channel, having an outer 'wall 26 and'tapering side walls 27, 28, thelatter being bent outwardly in opposite directions at the inner portion of the section to provide, respectively, longitudi- 20 closes the inner end of WedgeIIQ, and "former :23,

which is a'tapering channel, 'loses theburerender wedge 19. At the outer and inner points where formers 20, 23

cross the joggles 35, the latter are cut away.- The outer web of former 23 is joggled inwardly to abut the inner face of the outer transverse wall of section 16, as shown in Fig. 1.

Sections 14, 15 and 16, as best shown in Fig. 7, are each bent from sheet metal into box sections, adjacent edges of the inner walls of each being secured together by welds 33. The side walls of these sections similarly taper so that the exposed surfaces of the assembled sections lie along opposite sides and the narrowouter transverse side of an isosceles trapezoid. Aligned apertures or cut-outs 34 are provided in the transverse walls of the sections through which the spars and struts extend. As best shown in Fig. 1, the .outer ends of spar 10 and strut 11 terminate within section 15 and the outer end. of spar 11 terminates within section 16.

The spars and strut are channel shaped in cross section.

and taper in width to conform to the tapering inner surfaces of the side walls of the various sections, the inner ends of spars 10, 11, being welded, respectively, to plates 24, 25. The inner end of strut 12 is welded to the inner end of spar 11 and its outer end to the outer end of spar 10.

As best shown in Figs. 3 and 8, the front edges of the various sections terminate in joggles 35, front web 17 being disposed inside of same and the rear edges of V- shaped wedge member 19 disposed outside of same.

Channel shaped rear web 18 is tapered, similar to web 17, and disposed between the side walls of the box sections adjacent their rear edges, suitable rectangular cutouts 36 being provided in the transverse walls of the sections for receiving same.

Nozzle plate 37 is provided with a pair of 'rearwardly projecting pins 38 which extend through spaced apertures 39 in plate 24, permitting relative sliding movementtherebetween during temperature variations between the nozzle I and fin. Plate 25 is provided with a similar pair of apertures 40 through which a pair of bolts 41 extend, rigidly securing plate 25 to an annular ring 42 rigidly aflixed to the nozzle. Four equi-angularly spaced fin mountings of the type just described are provided around the nozzle plate and nozzle and four identical fins secured thereto.

In the assembly of the fin, plates 24, 25are rigidly affixed to a jig or fixture in the same relative positions in which they are disposed on the nozzle. Sections 13, 14, 15, 16 are stacked as shown in Fig. l and spar 10 inserted through the cut-outs 34 for receiving same. Strut 12 is then inserted through the cut-outs for receiving same and strut 11 similarly inserted. The assembly is then disposed on the jig and the various parts moved to predetermined position, as determined by gage stops and then spot welded together. The various formers and leading edge wedge are similarly aligned and welded. Since the sequence of assembly forms no part of the invention, per se, further detailed description is omitted in the interests of clarity, the foregoing merely being exemplary to show that the construction is subject to assembly and accurate alignment of its various components. 7 v

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be prac ticed otherwise than as specifically described.

What I claim is:

A stabilizing fin for use on a missile, comprising; a plurality of elongated box sections formed of sheet material, each being shaped as a substantially isosceles trapezoid in cross section and of the same cross section throughout its length, and of greater height between the transverse parallel walls than in transverse thickness between the tapering side walls, adjacent sections, in a direction toward an outer edge of the fin, being of diminishing thickness and disposed in superposed relationship, with the narrower transverse wall of one section abutting the wider transverse wall of an adjacent section, aligned apertures in certain of the parallel walls, reinforcing members disposed within the sections and extending through certain of the apertures, means securing the sections and reinforcing members together to form a unitary structure, said reinforcing members including a pair of spars and a strut extending between an outer end of one of the spars to an inner end of the other spar, a plate secured to an inner end of each spar, means rigidly securing one of the plates to a rocket nozzle in a predetermined alignment, and means for slideably securing the other plate to the rocket nozzle in such manner to permit relative motion between the nozzle and fin under temperature differences between the fin and nozzle, but maintaining the fin in said alignment.

References Cited in the file of this patent UNITED STATES PATENTS 2,381,456 Langdon Aug. 7, 1945 2,433,999 Marhoefer Jan. 6, 1948 2,459,357 Bell Jan. 18, 1949 2,482,130 Skinner Sept. 20, 1949 2,485,870 Edson Oct. 25, 1949 

